RE: 6MAN WG Last Call:draft-ietf-6man-ipv6-subnet-model-00.txt

"Wes Beebee (wbeebee)" <> Mon, 09 November 2009 18:32 UTC

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Subject: RE: 6MAN WG Last Call:draft-ietf-6man-ipv6-subnet-model-00.txt
Date: Mon, 9 Nov 2009 13:32:22 -0500
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From: "Wes Beebee (wbeebee)" <>
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Regarding "Note that Redirect Messages can also indicate an address is off-link."
I think we've removed that from the latest draft, which is available at

We have instead, the text (in section 2.2):
"Note that Redirect Messages do not contain sufficient information to signal that an address is off-link."

Could you please point to the section of
where you have found the text you were pointing to?

- Wes

-----Original Message-----
From: [] On Behalf Of JINMEI Tatuya / ????
Sent: Sunday, November 08, 2009 7:33 PM
To: Brian Haberman
Cc: Bob Hinden;
Subject: Re: 6MAN WG Last Call:draft-ietf-6man-ipv6-subnet-model-00.txt

At Tue, 27 Oct 2009 06:24:47 -0400,
Brian Haberman <> wrote:

>       Title     : IPv6 Subnet Model: the Relationship between
>                   Links and Subnet Prefixes
>       Author(s) : H. Singh, et al.
>       Filename  : draft-ietf-6man-ipv6-subnet-model-05.txt
>       Pages     : 11
>       Date      : 2009-05-15
> as a Proposed Standard.  Substantive comments and statements of 
> support for advancing this document should be directed to the mailing list.
> Editorial suggestions can be sent to the document editor.  This last 
> call will end on October 14, 2009.

I've read the latest version of the draft and support for advancing it.  I'm glad this document now focuses on its original issue (and sorry for the process delay if it was due to my objection to previous versions and my slow responses).

I have one minor technical comment.  In Introduction the draft states:

   In addition to the Prefix List, individual addresses are on-link if
   they are the target of a Redirect Message indicating on-link, or the
   source of a valid Neighbor Solicitation or Neighbor Advertisement
   message.  Note that Redirect Messages can also indicate an address is
   off-link.  Individual address entries can be expired by the Neighbor
   Unreachability Detection mechanism.

Technically, (in my understanding) Redirect Messages do not directly indicate an address is off-link.  What they can indicate are:
1. an address is on-link
2. an address is reachable via a different router than the redirect

normally #2 means the address is off-link, but, again, technically, my understanding is that it doesn't have to be so.

Frankly, I don't understand the rationale of this note in this context in the first place (I don't see any problem even if we remove this sentence), but if the intent is to just note the role of redirect is not limited to show an address being on-link, I'd suggest rephrase the "Note that..." sentence as follows:

   Note that Redirect Messages can also designate an alternate better
   router to reach an address, in which case the address is normally

JINMEI, Tatuya
Internet Systems Consortium, Inc.
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